The first codebit tells Openbox to maximise all windows and lose their decorations. If you want to keep the decorations, don’t use the <decor> tags.

The second codebit (beginning with the line containing “dialog”) tells Openbox to exempt dialogs from maximisation. This works for applications that have their dialogs and prompts properly codified as such. Not all of them are properly done.

Additionally, you may want to exempt some specific apps from getting maximised. For example the messenger: